Metal working



C. L. SPORCK METAL WORKING May 25, 1965 7 Sheets-Sheet 1 Filed March 9, 1959 INVENTOR cm; L. 6'f fi K BY i ATTORNEYS y 25, 1965 c. SPORCK 3,184,940 METAL WORKING Filed March 9, 1959 7 Sheets-Sheet 2 441 EYS May 25, 1965 c. sPoRcK' METAL WORKING 7 Sheets-Sheet 3 Filed March 9, 1959 w mm a m m m U M Q May 25, 1965 c. SPORCK 3,184,940

METAL WORKING Filed March 9, 1959 7 Sheets-Sheet 4 a {K ma tar :2 ,X m

621w; L. .S'Pam ATTORNEYS "INV ENTOR-g May 25, 1965 SPORCK 3, 40

METAL WORKING Fil ed March 9, 1959 7 Sheets-Sheet -5 I i I37 INVENTOR C. L. SPORCK May 25, 1965 METAL WORKING '7 Sheets-Sheet 7 Filed March 9, 1959 INVENTOR CLAU$ L. 5PORCK BY W -M ATTORNEYS United States Patent 3,184,940 METAL WORKING Claus L. Sporck, Cincinnati, Ohio, assignor to The Lodge & Shipley Company, Cincinnati, Ohio, a corporation of Ohio Filed Mar. 9, 1959, Ser. No. 798,033 5 Claims. (Cl. 72-68) This invention relates to sheet metal working and in particular relates to new and unique shell-type or tubularshaped, closed-end articles formed from sheet metal and to new and unique methods and apparatus for producing the same.

Articles having the general configuration of the kind mentioned have wide commercial and military applications and have been produced heretofore by several of the conventional metal working techniques such as drawing, forging, extrusion, welding and the like. All of such conventional methods of working metal have intrinsic limitations and none per so are capable of producing a broad range of such configured articles having necessary physical and/ or metallurgical characteristics such as size, shape, Weight, strength, hardness, grain size, grain orientation and the like.

The techniques of forging, extrusion and welding have such serious limitations for the production of articles of the kind mentioned that manufacturing processes for the same have been largely confined to the drawing group, i.e., drawing, redrawing and ironing.

While the drawing group of sheet metal working operations have had, of necessity, wide industrial acceptance and use, the same are not without attendant limitations, particularly in producing a shell where the tubular section is of large length or height.

Drawing and redrawing are bottomed on the principle of successively reducing the diameter of a blank in a plurality of draws to a total reduction so that the height of the final shell falls generally within the range desired. In a single draw from a flat blank the maximum obtainable reduction of diameter varies between 35-47% and, even with maximum reduction, the depth or height of the article is relatively small and not exceeding, even under the most ideal conditions, about 50% of the diameter of the original blank. Where the height or the length of the article is such that redrawing or successive reduction in blank diameter is required, very substantial problems arise, particularly because of the strain hardening phenomena. For example, successive draws have a cumulative effect as to strain hardening and this may reach a state where further reduction of blank diameter is impossible. Sol, in drawing operations the blank is annealed between each draw so as to relieve the work hardening. However, even with the relief provided by annealing, successive redraws must be done with successively decreasing percentage of diameter and as a consequence, changes in height arising out of the redrawing are correspondingly reduced. In other words, with redrawing while there is an increase in height with each draw, the successive increases are progressively smaller and smaller. Thus, in conventional drawing it is impossible to produce a shell-type article having a substantial height without a very large number of reductions in blank diameter.

Thus, in the drawing art the techniques of redrawing or reducing blank diameter have been expressed in terms of, and largely controlled by, percentage reduction of diameter rather than being controlled as a function of height, even though height is the ultimate objective in the process. In conventional drawing, we have the anomalous situation that even though the depth or height is the primary objective, it is attained only as a by-product of diameter reduction.

3,1843% Patented May 25, 1965 Broadly speaking, this situation has been due to the failure to critically coordinate the size and shape of the initial blank, the size and shape of the final and/or any intermediate blank or shell and the tooling therefor, so as to minimize the undesired effects of strain hardening. In another way this situation is due to the failure to coordinate the size and shape of the initial blank and the final or intermediate blanks and the tooling therefor as a function of the desired height of the ultimate shell.

The present invention is a departure from the techniques and philosophy of prior methods, particularly drawing-type of operation for making shell-type articles. The invention contemplates an integrated and interrelated series of steps and blank shapes coordinated so that the desired ultimate diameter is fixed in the initial blank and remains constant throughout the forming operation with the desired height of the final shell being the essential control factor for all of the operations.

In one broad aspect the invention contemplates the making of large-height, shell-type articles by the use of two principal or major coordinated operations. One operation involves the forming of an especially configured blank and the other involves the reforming of this blank into shell or tubular shape. Both operations have special and important inter-dependence and relationship which governs the size, shape and form of the appropriate forming tools. More specifically, the invention contemplates the forming of a blank having a conical-shaped part made by way of axial displacement and that this axially displaced conical part be subjected to forces which reduce its included angle and increase its length until the same assumes a tubular shape. For this purpose the invention contemplates that having the height, and of course the diameter, of the desired shell, the tools for forming the tube and the tools for forming the cone can be quickly and easily determined by means of certain mathematical relationships.

In another aspect the invention contemplates the making of large-height, shell-type articles by starting with an axially displaced cone, the minor diameter of which is the same as the diameter of the desired shell; reforming all but a small part of the nose end of the cone into a tubular form whose diameter is larger than that of the desired shell; while maintaining the minor diameter, reforming the nose end into tubular shape to form part of the desired shell; successively reforming adjacent parts of the first tube into cones of the same dimensions as the nose; and then while maintaining the minor diameter, reforming these cones into tubular shapes to form the remainder of the desired shell.

In another aspect the invention contemplates the making of large-height, shell-type articles by the forming of a cone and then reforming the cone into tubular shape, the reforming of the cone being controlled so that a known elongation takes place as the cone assumes the tubular shape.

In another aspect the invention contemplates the forming of shell-type articles by the critical inter-relation of the shapes of the initial blank and the article formed therefrom, such shapes being coordinated with the manner of forming to provide for maximum change in height or length with minimum force or work.

In another aspect the invention contemplates methods and equipment for forming relatively long shell-type articles by successively forming a blank into a plurality of like conical shapes and reforming these into tubular shape so that elongation takes place, the elongation being wholly within the control of the forming technique.

In another aspect the invention contemplates the forming of a shell-type article by first forming an axially displaced cone, the small end or nose of which has the diameter of the shell or tube to be formed and then while ables the forming of a shell-type article having a height 1 and diameter never attained by conventional techniques.

Another advantage of the invention is that it enables the forming of shell-type articles in any of a wide range of diameters and large heights with an absolute minimum of working operations.

Another advantage of the invention is that it enables the forming of a shell-type articles with a minimum of materials, tooling and labor, resulting .in substantial savings in manufacturing costs.

Another advantage of the invention is that it enables the production of a shell-type article having extremely large height and a relatively thin wall.

Another advantage of the invention is that it enables the production of a shell-type article having an extremely large height and relatively thin wall with an absolute minimum of operations and equipment.

Another advantage of the invention is that it enables the production of shelltype articles by the cold working of metal which cannot be satisfactorily worked by conventional methods.

Another advantage of the invention is that it enables the production of large-height, shell-type articles by methods and equipment arranged so that the power requirements are reduced to an absolute minimum.

Another advantage of the invention is that it enables the production of shell-type articles in any of a wide range of dimensionally accurate diameters and heights.

The invention, particularly the preferred form of the methods and equipment and the articles formed thereby, will be understood from the following description and drawings wherein:

FIGURE 1 is an elevational view of a typical machine for carrying out certain of the forming or shaping operations of the invention with certain of the control mechanism for the machine illustrated in diagrammatic form;

FIGURE 2 is an enlarged, vertical, sectional, elevational view of certain portions of the machine of FIG- URE 1;

FIGURE 3 is a plan View of part of the machine illustrated in FIGURE 2;

FIGURE 4 is an elevational, sectional view illustrating equipment for use in certain of the forming operations of the invention;

FIGURES 5 through 7 are sectional, elevational views of tooling for use in certain of the forming operations of the invention and illustrating different relative positions of the tools during the forming operation;

FIGURE 8 is a sectional, elevational view illustrating equipment along the lines of the equipment of FIGURE 4 but in modified form and being for use in one of the forming operations of the invention;

FIGURES 9 through 11 are sectional, elevational' views of tooling along the lines of the tooling of FIG- URES 57 but in modified form and being for use in certain of the forming operations of the invention and illustrating different relative positions of the tools during the forming operation; FIGURE 12 is a sectional, elevational view of equip- :ment along the lines of that of FIGURES 4 and 8 but in modified form and being for use in certain of the forming operations of the invention;

FIGURES 13 through 17 are sectional, elevational views of tooling along the lines of that of FIGURES 5-7 and 9-11 but in modified form and being for use in certain of the forming operations of the invention;

FIGURES 18 and 1801' are longitudinal sectional views til and illustrating in particular the forming of a shell-type article from a conical-shaped blank in a single forming operation;

FIGURES 19, 19a and 19b are longitudinal sectional views and illustrating in particular the manner in which the length or height and included angle are successively changed in two forming operations to produce a shelltype article;

FIGUREQO is an isometric view of a conical-shaped blank in certain stages of a forming operation; and

FIGURE 21 is a view looking from the left-hand end of FIGURE 20.

Before describing in detail the preferred steps in the methods of the invention and the preferred apparatus for carrying out the same, I will first refer to the various stages of blank formation as the same is being worked into a shell or tubular-shaped, closed-end article in order to establish certain terminology and identify dimensions. This will be done in connection with FIGURES 18 through 19b.

In FIGURE 18 a fiat blank B isaxially displaced so as to form the conical-shaped blank C. The diameter of the cone or blank is designated as D and this is the same as the large or major diameter of the'cone C. The small or minor diameter of the cone C is designated as d. The angle a is one-half the included angle of the cone.

The slant height of the cone is designated by I1 and this,

slant height, in the axially displacing process, is flowed from the material of the portion designated by h.

The blank C is then worked or formed into a hollow, annular shape such as the tubular shell S of FIGURE 18a. The letter H designates the length or height of the shell S and the diameter of the shell is the same as the minor diameter d of the cone .C and is designated as such.

The letters D, d, I1 h and H will be used throughout the description to designate corresponding parts of similar cones and shells.

As will be apparent from the above, the flat blank B was flowed into a cone C and then reformed into the shell S. The invention contemplates that the desired shell be'made by more than one reforming operation as will be noted from the following.

In FIGURE 19 the fiat blankB is axially displaced into a blank C The diameter of the blank B and the major diameter of the cone C are designated as D. The minor diameter of the cone is designated as a, the slant height as I1 and one-half the included angle of the cone as a.

The blank C is then reformed into a hollow, annular shape such as the blank RF having a tubular section and a conical section as shown in FIGURE i. In FIGURE 19a the length or height of the tubular section is designated as H and its diameter as d The smaller diameter of the conical section is designated by d since this is the same dimension as the minor diameter of the cone C The blank RF is thensubsequently worked into a hollow annular shape such as the shell S as shown in FIGURE 1%. The height or length of the shell is designated as H and the diameter, which again is the same as the minor diameter of the cone, is designated as d.

Turning now to the description of certain of the equipment used in the forming operation, I have shown in FIG- URE 1, somewhat diagrammatically a typical machine which may be used for forming a conical-shaped blank into a shell-type article. In connection with FIGURES 1-3, it will be presumed that the conical blank and shell are the same (on an enlarged scale) as the conical blank C and shell S of FIGURES 18, and 18a.

The machine has a base 20 carrying four vertically extending strain rods 21,22), .23 and 24. Just above the base 20 there is a table 25'fixedly connected to the strain rods and at the top of the rods there is a crown 26 held on the strain rods by the nuts 27. The table 25 carries an outer forming tool 30 which has certain forming surfaces 31 and an aperture 32 is formed in the table 25 in alignment with the forming surfaces 31. Slidably mounted on the strain rods is a platen 33 carrying an inner forming tool 34 which is provided with forming surfaces 35 and an inner aperture 36 within which is a forming tool 40.

The forming tools 34 and 4d are adapted to be moved up and down as described following.

On the crown 26 there are two cylinders 41 and 42 which respectively carry the pistons 43 and 44 whose rods 45 and 46 are connected to the platen 33. By controlling the fluid in the cylinders 41 and 42 the platen 33 and forming tool 34 are moved up or down. In the position of the platen and tool as shown in FIGURES l and 2, a cone-shaped blank C may be loaded into the forming tool in cooperative engagement with the surface 31 (see FIGURE 2). The down position of the platen 33 is indicated by the dotted lines in FIGURE 2 and at this time the surface of forming tool 34 is in close cooperative engagement with the blank C.

The crown 26 carries another cylinder 51 having a piston 52 with a rod 53, the lower end of which constitutes the forming tool 40. By controlling the fluid in the cylinder 51 the forming tool is moved up and down. In FIGURE 1 the forming tool is in its upmost position and its lowermost position is indicated by the dot-dash lines a in FIGURES 1 and 2.

As will be explained more in detail later, when the tool 40 has moved down so that the surfaces 31 and 35 are in cooperative engagement with the cone C, the tool 46 engages the flat end of the cone and continues to move down to move the cone through the tools 30 and 34 to reform the same into the shell S.

The equipment for controlling the fluid in the cylinders 41, 42 and 51 will be next described.

In the main this comprises a pump 54 connected to a reservoir 55, a solenoid-operated control valve 56, a solenoid-operated relief valve 57 and certain electrical lines generally indicated by 58. The solenoid 60 for the valve 56 is controlled by a switch 61 and also by a switch 62. The solenoid 63 for the valve 57 is controlled by a switch 64.

In the position of the components as shown, the switch 61 has first been actuated to energize the solenoid 60 which actuates the valve 5s so that the fluid in cylinders 41, 42 and 51 flows in a manner to move the tools 34 and 40 down as will be explained following.

As to the tool 34: The cylinders 41 and 42 have lines 65 and 66 which are connected through a pressure regulating valve 70 to a line 71 running to the valve 56. As will be apparent, the spool 72 of the valve 55 has been positioned by the solenoid 60 (to the left) so that the line 71 is in communication with the line 73 running to the discharge side of the pump 54. Thus, fluid from the pump can flow into the top sides of the pistons 43 and 44. The fluid in the lower ends of the cylinders 41 and 42 can flow to drain. The lower ends of the cylinders 41 and 42 are connected to lines 74 and 75 which are both interconnected to a line 76 which is in turn connected to a line 80 running to the valve 56 and a line 81 running to the relief valve 57. As will be seen, the spool '72 is positioned to connect the line 80 to a line 82 which runs to the reservoir 55. The tool 34 moves down until it engages the cone C.

As to the tool 40: The upper part of the cylinder 51 is connected to a line 83 having a regulating valve 84 and connected to the line 71. As mentioned above, fluid from the pump 54 is flowing through the line 71 and this can flow into the top part of the cylinder 51. Fluid in the lower part of the cylinder is metered out via the line 85 which is connected to the line 76 running to reservoir as mentioned above. The tool 40 moves down and engages the flat end 50 and continues to move down to the position shown by the dot-dash lines 40a. At this time the shell S is pulled off the tool 40. The operator then actu- 6 ates the switch 62. This causes the tools 34 and 40 to move up as explained following.

The solenoid 60 moves the spool 72 of the valve 56 to the right-hand side. At this time the direction of fluid flow to and from the cylinders 41, 42 and 51 is reversed in that the line 71 is connected by the spool 72 to the drain line 32 and the line 80 is connected by the spool 72 to the pressure line 73. The components then move to the position shown in FIGURE 1. As soon as another blank or cone is loaded into the tool 30, the switch 61 is actuated to repeat the cycle.

If the forming tool and the platen 33 are to be held in the up position for a substantial period of time, the holdup pressure on the pistons can be cut down by the machine operator energizing the switch 64 which actuates the solenoid 63 to move the spool of the valve 57 to the right so that the line 81 is connected to the line 91 running to reservoir. Thus, the fluid flowing through line 80 to the line 76 to the bottom part of the cylinders 41, 42 and 51, is partially diverted back to sump. The valve 57 controls the flow so that the unit pressure in lines 81 and 76 and the cylinders is just sufficient to maintain the upward position. When the machine is again ready for operation the operator actuates the switch 64 so as to move spool 90 of the valve 57 to the position as shown.

The manner in which the tools 30, 34 and 40 are preferably constructed will be apparent from a discussion vof the forming tools mentioned in connection with FIG- URES 4-7 below. It will be assumed that the forming tools and various blanks of FIGURES 4-7 are the same as those of FIGURES l and 2 but on an enlarged scale. For purposes of illustration the forming tools of FIG- URES 4-7 are turned 90 from the position in FIGURE 1. The FIGURES 4-7 illustrate the preferred method and equipment for the making of a shell with a flat or cup-shaped blank with only a single reforming operation.

As mentioned heretofore, the invention contemplates that the initial blank have a part which is in conical form and that this conical part be made by the axial displacement technique. The manner of doing this to make the blank C is illustrated in FIGURE 4.

A conical-shaped rotatable mandrel or spindle is adapted, in conjunction with a rotatable tailstock 101, to support a flat blank B (or a cup-shaped blank B With the spindle, blank and tailstock rotating, a roller 104 is caused to engage the blank and then move in a path parallel to the surface of the spindle to a position indicated at to axially displace or elongate and reduce the blank B into the blank C having the conical-shaped part 106.

The term axially displace means in general that the various strata of the wall of the blank B are all forced to assume positions which are generally parallel to the rotational axis of the spindle and extend circumferentially in helix-like form along the spindle axis. The techniques for axial displacement are known and are disclosed in my copending application 650,277, filed April 2, 1957, and entitled Methods for Working Sheet Metal, now abandoned.

The forming of the blank by axial displacement is important for several reasons. For example, the conical part 106 can be made dimensionally accurate in wall thickness, included angle, slant height and major and minor diameters. The importance of this dimensional accuracy will be more clearly apparent as the description proceeds.

Insofar as determining the Wall thickness and length of the section 106 is concerned, the following should be noted. Where a fiat blank such as B is used the thickness may be calculated from the formula t =t sine a, where t is the original thickness of the blank; 1 is the final thickness; and angle cc is one-half the included angle of the cone or spindle. The slant height k may be calculated from the formula 7 where Where a cup-shaped blank such as B; is used the wall thickness of the conical part may be calculated in accordance with the formula sine a sinefi where T is the thickness of the original blank; T is the thickness of the finished cone; angle {3 is one-half the included angle of the conical-part of the blank; and angle a is one-half the included angle of the spindle or finished.

cone. For further details with regard to the above-mentioned dimensions, my copending application may be consulted.

The blank or cone C is placed in the inner forming tool 30 shown in FIGURE and then the. inner forming tool 34 and movable forming tool 4% brought up to the posi tions as shown. This represents the starting position for the reforming operation. With continued movement of the forming tool 41 (to the right in FIGURE 5) the coniterminatesat its lower end in a circular-shaped aperture 113 which in the embodiment shown, is extended axially and constitutes a cylindrical surface. The surface 112 and the aperture 113 are coaxial with the axis A of the conical blank C.

The surface 112 is machined so that it conforms identically with :the outer conical surface of the part 106 as it is desirable that the outer surface of part 1% is wholly engaged with the surface 112. The advantage of the axial displacement in producing dimensional accuracy in the part 1061Will therefore be appreciated. The diameter of the aperture 113 is made to correspond to the outside diameter d of the shell to be formed.

The forming surface 35 of the tool 34 is machined to correspond exactly to the outer conical surface ofthe spindle 160 or to the inside surface of the conical part 106.

As the start position as shown, the surface 112 and 35 are adjacent one another but separated by the wall thickness of the part 106, the part 106 of course being disposed in the space 107 between these surfaces. In the start position the force developed by the pistons 43 and 44 may be such that the surface 35 is in tight engagement with the inner surface of the part 166 so as to exert a force or pressure thereon. On the other hand, the force exerted by the surface 35 maybe negligible and only an amount necessary to keep the outer surface of the part 106 in engagement with the surface 112 and the surface 35 in engagement with the inner surface of the part 166,

but suflicient to maintain this relationship during the sub-. sequent forming operation.

The exact amount of force exerted by the tool 34 depends to a large extent on the type of metal being worked and its susceptibility to strain hardening.

The reforming operation commences as soon as the movable forming tool 40 moves from the position shown in FIGURES. At this time the tool 413 exerts a thrust on the end 50 of the blank C and begins to move the same through the aperture 113 and also starts to force the wall of part 166 through the space 107 toward the small end. This has the effect of reducing the included angle and elongating the first small increment of the part 106 that.

enters the. aperture so that the same assumes .atubular shape and then this is continually repeated as more and more of the part 106 moves through theaperture; This operation continues until such time that the includedangle of all portions of the part 106 is changed and the wall of part 106 elongated or has assumed the tubular shape 111 as shown in FIGURE 7. V

The forces exerted on the. part 106 by the reforming operation for changing included angle and elongating are somewhat diagrammatically illustrated in FIGURE 21 which is an isometric representation of the stage of forming shown in FIGURE 6. In FIGURE 21 thedotted lines and 121 define a small section of the conical part of the blank and the dotted lines 122 and 123 represent a portion of the conical partthathas been formed into tubular shape. As the conical part 166 is forced into and through the aperture 113 there are tensile forces set up in the increment being elongated. These tensile forces are represented by the arrow F Also, there arecompression forces set up in the increment just entering the aperture asrepresentedbythe arrows F From an inspection of FIGURES 20 and 21. it willbe seen. that the tensileforces act in a direction along the axis A while the compression forcesact in a direction around the axis A.

In the reforming operation describedabove there is substantially no change in wall thickness of the part 106 as it is reformed into the tubular section 111, particularly where the tools 30; 34 and 49 are properly designed; V The wall thickness T of the shell S can be considered the same as the wall thickness tof the cone C.

In FIGURES 8-11 I have shown amodified form of the, method explained in connection with FIGURES 4- '7. In this embodiment the closed end of the shell has a conical shape rather than a flat shape as'has the shell of FIGURE 7.

In FIGURE 8 I have shown a conical-shaped-spindle 'and a tailstock 131 which are adapted to support a flat blank B (or a cup-shaped blank B The blank B is then axially displaced by a roller (in the same manner as explained in connection with FIGURE 4) to form the blank C having the conical-shaped part 135.

In FIGURE 9'the outer forming tool and the inner forming tool 141 are substantially the same as those shown in FIGURE 5. However, the-movable forming tool has a conical-shaped nose 132 which fits into the nose or small end of the blank C as showrn When the movable tool 141 is moved (to the right) only that portion of the conical part 135 to the lefthand side of the aperture 143 is changed from conical form to tubular form, as is shown in FIGURES 10-11 which. represent successive movements of the tool 142.

Thus, it will be seen in FIGURE 11 that the formed blank C has a tubularsection 145 and a conical section 146. While I have shown the section 146 to be conical, it willbe understood that the invention contemplates the forming of other shapes. For example, the section146 may have a bowl shape as indicated by the dotted lines 1511. In such instance the bowl shape would be accomplished during the first operation, that is, the axial displacement ofa fiat blank toforma blank having a conical part. In such instances the spindle13tl of FIG- URE 8 is modified so that the nose is rounded and the roller, in, forming the round end, is made to follow a path which is non-parallel to the rounded surface. but axially spaced therefrom a distance equal to the original thickness of the blank. This particular movement of the roller is continued until the rounded section is formed and then the roller is moved parallel to the surface of the spindle in the same manner as explained in connection with'FIGURES 4 and 8. For further information on the details of forming such a bowl-shaped section reference may be had to copending application 454,871, filed September 9, 1954, now Patent No. 3,114,342.

With reference to FIGURES47, I will explain the manner in which the size and shape of the initial conical blank and the size and shape of the tools for forming this blank into a shell are determined.

The starting point is the height H, the diameter d and the thickness T of the desired shell-type article. The dimension D may be determined from the formula: D= /4dH sine oc+d The values of d and H are substituted in the formula and then the value of angle a is selected. Usually the angle should be between and 45 with 17 to 23 being the preferred range. I

For example, assume that the shell required was to be made from 302 stainless steel with an H of 7.125", a d of 3" and wall thickness T of .0 4- Assuming that a is and substituting the value of H and d and on into the formula, we find that the necessary blank diameter is 6.18". Since the required wall thickness T of the shell is to be .042", this is the wall thickness of the cone and therefore the thickness of the blank can be calculated from the formula t=t sine a. Substituting the values of t and or in the formula, we find that t or the blank thickness would be .125". The slant height is 4.65" from the relationship D-d Ill-2 sine a With this information then, the spindle 100 is designed with an included angle of 40 and a length necessary to form the slant height. In the axial displacement operation the roller is run at a path parallel to this surface but spaced therefrom a distance of .125. This operation then forms a conical-shaped blank having the required size and dimensions necessary to form the desired shelltype article.

The forming tools and 34 are designed to accept the blank between the conical surfaces. The diameter of the aperture 113 is made the same as the diameter d and the outer diameter of the movable forming tool is equal to the diameter d less twice the wall thickness of the shell.

In connection with the method explained in connection with FIGURES 8-11, the same techniques for determining blank and tool size are used. The end section 146 has no part in the calculation (except in the sense that its included angle may have to be of a certain value).

Assuming that the dimensions of the tubular section 145 of the shell S are to be the same dimensions as the shell S and that the end 146 of the shell S is to have an included angle of 40 (or equals 20), such a shell could be formed from a cone having the same dimensions as the cone C. However, the nose 146 must be formed into the shell. Therefore, the reforming operation must start at a point on the cone C which has a diameter the same as that desired in the shell, namely 3" in this case. Tools 140 and 141 are designed to accept and position the cone or blank C so that the same is correctly positioned with respect to the aperture 143. Also the head 142 of the tool 141 must be dimensionally accurate so that the reforming starts at the proper point.

In designing the spindle 130 the necessary metal for the section 146 must be taken into account and this may be done by making the spindle 13f) of sufficient length so that when blank B is worked by the roller the section 146 will be formed into the blank C As has been indicated, the slant height of the cone increases as the same is reformed into a shell. In reforming certain precautions are necessary in order to avoid cracking or splitting due to excessive elongation. This increase in height is equal to the difference between the height of the shell and the slant height of the cone, i.e., Ah=Hh (see FIGURE 18a). The percentage increase in height of k when it is formed into the shell, is given as susceptibility to strain hardening.

In a single reforming operation the maximum height is given by H ixh where K is Where K is a constant and its value depends upon the type of metal being worked. For 302 stainless steel K is approximately 1.53". The K factor can be determined for other metals by reforming several cones of the same minor diameter d and the same angle a but varying the major diameter D; i.e., varying the slant height h until the maximum ratio of Ah/ I1 without cracking is found.

In FIGURES 12-17 I have shown how the invention may be applied in those instances where the height of the desired shell is such that the shell cannot be formed in a single reforming operation. In connection with FIG- URES 12-17, it will be presumed that the flat blank, the conical blank, the reformed blank and shell are the same (on an enlarged scale) as the blank B conical blank C reformed blank RF and shell S of FIGURES 19-19b.

In FIGURE 12 the spindle and the tailstock 181 support the flat blank B (or a cup-shaped blank B A roller is made to axially displace one or the other of these blanks into a blank C having a conical-shaped part 185.

The blank C is then supported (FIGURE 13) by the outer forming tool 136 and the inner forming tool the outer forming tool having the circular-shaped aperture 121. The movable forming tool 192 has a head 193 which fits into the nose section 194 of the blank. The diameter of the tool 192 is larger than the diameter desired in the finished shell. The tool 192 is moved to the right which then reforms the blank C into the blank RF (FIGURE 14) having a tubular-shaped section 196 and a conical-shaped section 200.

The blank RF is then supported as shown'in FIG- URE 15 between the outer forming tool 201 and the inner forming tool 202, the outer forming tool having the circular-shaped aperture 293 and the movable tool 204 having a diameter corresponding to the diameter desired in the finished shell.

The outer forming tool 201 has a conical-shaped surface 205 and the inner tool 202 has an adjacent conicalshaped surface 206 within which is supported the conical section 2%. The outer forming tool also has cylindricalshaped surface 21% and the inner forming tool has an adjacent cylindrical-shaped surface 211 between which is supported the tubular section 196 of the blank.

In FIGURE 16 the movable tool 204- is shown as moved to the right. This movement causes the conical section 200 to move through the aperture 203 and be re formed into tubular shape 212 which forms part of the desired shell. This motion to the right also moves the tubular section 196 between the conical surfaces 205 and 206 and begins to reform the tubular section 196 into a conical shape which is the same as the section 200. As this portion is then moved through the aperture 203 it is formed into tubular shape and constitutes an additional portion 213 of the desired shell. Continued motion of the tool 204 to the right brings the other succeeding portions of the tube 196 into conical shape and then into tubular shape.

Finally, when the tool 204 has moved all the way to the right (see FIGURE 17) the desired shell S having the tubular section 115, is completely formed.

The following material deals with the manner in which it is determined whether a second reform section is necessary and with the manner in which the size blanks and tools of FIGURES 12 through 17 are determined.

In FIGURE 19b suppose the height H of the shell is 14.6" and the diameter d is 2.5". For present purposes the wall thickness can be ignored; however, this can be determined as explained heretofore. Assume that the angle of the cone to be formed is 17, then by Assume that the part is to be of 302 stainless steel then by H Kh or 2 sine o:

the maximum height is 11.8".

Since the required height is 14.6" and a height of 11.8" is the maximum permissible, an additional reform (FIG- URES 19a, 13 and 14) is necessary. For the height H of the first reform, it is desirable to select a value which is somewhat less than the maximum obtainable. This preferably is 75% and thus H =75% 1l.8"=8.85".

With H =8.85" then d (the diameter of the reform tubular section) can be determined from the relationship The blank C must be reformed to blank RF (FIG- URES 19a, .13 and 14) by starting at a point having a diameter of 3.52. This diameter (together with a and the slant height of cone 0,) determines the dimensions of the tools 186, 199 and 192. The diameter of aperture 191 is 3.52" and the outer diameter of the tubular part of the tool 192 is less than 3.52 by twice the wall thickness. For the final reform into the shell 8, (FIGURES 15, 16 and 17) the tools 2%, 262 and 2% must be designed to accept the blank RF with the aperture 203 having the same diameter (2.5") as the diameter of the required shell and the diameter of tool 204 appropriately smaller.

The process shown in FIGURES -17 will reform the blank RF into the shellS having the required diameter and height. The height H of the shell S is in accordance with the following formula:

d 4d sine a In connection with the various formulas mentioned above, it is desired to emphasize the well-known fact that metal being deformed in a metal working operation does not always respond exactly as predicted by theoretical considerations. In the present process, therefore, some small variations may be expected. For example, a reformed blank may not have a true uniform wall thickness and, hence, a height not exactly as predicted by the appropriate formula. Such variations, of course, can be compensated for in the design of the tools and in the equipment for supporting and/ or moving the same.

In the discussion above it will be noted that I have not set out any tolerances for the various tools. Such tolerances may depend upon the dimensional accuracy required in the final shell, the shell material, the tool material, etc. Tolerance requirements will be understood by those skilled in the tool art. In addition, it is to be observed that in many of the above-described forming operations the tools and blanks may be lubricated, for example with an oil and molybdenum mixture.

Also, it is pointed out that an annealing treatment may be required between certain stages of the working operations. :For example, in the making of a long shell such as S of FIGURE 1% of stainless steel 302, it is desirable to anneal the cone C beforereforming the same into the blank R-F. Annealing should be carried out so as to retain some of the elfects of the strain hardening due to the axial displacement. Strain hardening also takes place with the forming of the blank RF and this blank may then be annealed before the final operation. Unless it is required by the specifications for the shell or the degree of strain hardening, it is preferable not to anneal the final shell. In this way the beneficial effects of strain hardening are retained. I have not gone into the question of annealing'in detail because the techniques of such operations are well understood by those skilled in the art.

In connection with FIGURES 6, 10 and 16 it is pointed out that the movable tool maybe stopped in the position shown so that the various blanks retain the indicated configurations. This general type of blank has special advantage in many situations, for example, as a can or casing for a sealed motor or for forming a venturi-type article as disclosed in my copending application, filed concurrently herewith and entitled Metal Working, now Patent No. 3,120,206.

Before closing I will give an. example to compare the forming of shells by way of the present invention and the forming of the same shells by conventional drawing methods. Thiswill illustrate several of the unique advantages of the invention.

It will be recalled in connectionwith FIGURES 4-7 that the dimensions of the shell were H=7.125", d=3 and the wall thickness is .042";

Using the techniques of the present invention, the shell would be manufacturedwith the following operations:

( 1) Squareshear a 6" 6-' -.02S" flat blank (2) Axially displace the blank B to form the cone C (3) Wash the cone C ('4) Anneal the cone C- (5) Trim, if necessary, and (6) Reforming operation.

By conventional drawing methods the shell would be made with the following operations:

(1) Square shear a 9% 9 .060" blank. (2) Ring shear the blank to a 9" diameter (3) First draw (4) Wash the drawn blank (5) Anneal the drawn'blank (6) Second draw (7) Wash the drawn blank (8) Anneal the drawn blank (9) Trim, and

(1 0) Third or. final draw.

It will be once be apparent that the present invention provides tremendous advantage in savings of material, labor and tooling. The above-described shell made by my invention can be soldat about 70% of the cost of the shell made by drawing. Furthermore, with my invention, the tooling andnum'ber of operations used in manufacture are a minimum. Also, the horsepower required in the equipment for axially displacing a cone andthen reforming the cone into a shell is substantially less than the horsepower which must be available for conventional draw work. Thus, the capital equipment'can be significantly smaller and, hence, lower in cost.

I claim:

1. The method of forming an article of manufacture having a tubular section comprising the steps:

spin forming a'blank against a rotating spindle by forcing strata thereof to assume positions which are generally parallel to the rotational axis of the spindle and extending in helix-like form along said axis to form the same into a conical shapedpart, the major diameter of the part being given by /4dH sine a+d and exerting on said conical shaped part compression forces acting around its axis and tensile forces acting along its axis to gradually form the conical part into tubular shape and thereby form said tubular section and exerting said forces so as to maintain the included angle in the unworked portion of the part and to cause the diameter. of, the tubular section to *be the same as the minor diameter ofv said conical-shaped part, the variables of said formula being defined as: d=the minor diameter of said conical shaped part; H =the height or length of said tubular shape; and a= the included angle of said conical shaped part. i

2. In a method of forming an article of manufacture having a tubular section, the steps of:

spin forming a blank against a rotating spindle by forcing strata thereof to assume positions which are generally parallel to the rotational axis of the spindle and extending in helix-like form along said axis to form the same into a conical shaped part;

exerting on one section of the conical shaped par-t compression forces acting around the axis of the part and tensile forces acting along the axis of the part to gradually form the section into tubular shape, said one section of the part being located between the major diameter of the part and a diameter intermediate the major and minor diameters of the part and exerting said forces so as to maintain the included angle in the unworked portion of said one section and to maintain said other section of the conical shaped part in its original conical form, said intermediate diameter being given by where 2 H =the height or length of said tubular shape; u= the included angle of said conical shaped part; and D=the major diameter of said conical shaped part. 3. In a method of forming an article of manufacture having a tubular section comprising the steps:

spin forming a blank against a rotating spindle by forcing strata thereof to assume positions :which are generally parallel to the rotational axis of the spindle and extending in helix-like form along said axis to form the same into a conical shaped par-t; exerting on one section of the conical shaped part compression forces acting around the axis of the part and tensile forces acting along the axis of the part to gradually torm the section into tubular shape, said one section of the part being located between the major diameter of the part and a diameter intermediate the major and minor diameters of the part and exerting said forces so as to maintain the included angle in the umworked portion of said one section and to maintain said other section of the conical shaped part in its original conical form, the intermediate diameter being given by where H =the height or length of said tubular shape;

a= the included angle of said conical shaped part; and

D=the major diameter of said conical shaped part;

and

diameter of the tubular form to be the same as said minor diameter;

exerting on said one section compression forces acting around said axis and tensile forces acting along said axis to gradually form the one section into a conical form which is the same form as said other section; and

then repeating said third step on last said conical form.

4. The method of forming an article of manufacture having a tubular section comprising the steps:

spin forming a blank against a rotating spindle by forcing strata thereof to assume positions which are generally parallel to the rotational axis of the spindle and extending in helix-like form along said axis to form the same into a truncated cone of predetermined wall thickness;

starting at a diameter intermediate the major and minor diameters of said cone gradually working the wall of the cone into a tube having said intermediate diameter and said wall thickness and carrying out said working while keeping the remainder of the cone in its original shape; and

gradually working said remaining part and then said tube part into a tubular section having said wall thickness, the working maintaining, the diameter of the tubular section the same as said minor diameter.

5. In a method of forming an article of manufacture having a tubular section, the steps of:

spin forming a blank against a rotating spindle by forcing strata thereof to assume positions which are generally parallel to the rotational axis of the spindle and extending in helix-like form along said axis to form the same into a conical-shaped part of predetermined wall thickness;

gradually working a segment of the wall of said conicalshaped part into a firs-t tubular section having said wall thickness and a diameter larger than the minor diameter of said conical-shaped part; and

then gradually working the next adjacent segment of the Wall of said conical-shaped part and said first tubular section into a second tubular section having said wall thickness and a diameter smaller than first said diameter;

said gradual working being in a direction from the closed to the open end of said conical-shaped part and the selection of said adjacent segments being progressive from said open end to said closed end.

exerting on said one section compression forces acting around said axis and tensile forces acting along said axis to gradually form the one section into a conical [form which is the same form as said other section; and

then repeating said third step on last said conical for-m.

References Cited by the Examiner UNITED STATES PATENTS FOREIGN PATENTS 10/35 Great Britain.

OTHER REFERENCES Steel Cartridge Cases for 37 mm. Shell, American Machinist, July 22, 1943, vol. 87, No. 15, p. relied upon.

Forming Alcoa Aluminum and Magnesium, Aluminum Company of America, Pittsburgh, Pa, 1947 (p. 76 relied upon).

WHITMORE A. WILTZ, Primary Examiner.

JOHN F. CAMPBELL, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,184,940 May 25, 1965 Claus L. Sporck It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 7 line 50, for "surface" read surfaces column 8, line 45, after "tool" insert 141 column 13, lines 51 and 52, strike out "diameter of the tubular form to be the same as said minor diameter;" and insert instead exerting on said other section compression forces acting around said axis and tensile forces acting along said axis to gradually form the other section into tubular form and exerting last said forces so as to cause the diameter of the tubular form to be the same as said minor diameter; column 14, line 29, beginning with "exerting on "said" strike out all to and including "conical form." in line 34 same column 14.

Signed and sealed this 19th day of October 1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. THE METHOD OF FORMING AN ARTICLE OF MANUFACTURE HAVING A TUBULAR SECTION COMPRISING THE STEPS: SPIN FORMING A BLANK AGAINST A ROTATING SPINDLE BY FORCING STRATA THEREOF TO ASSUME POSITIONS WHICH ARE GENERALLY PARALLEL TO THE ROTATIONAL AXIS OF THE SPINDLE AND EXTENDING IN HELIX-LIKE FORM ALONG SAID AXIS TO FORM THE SAME INTO A CONICAL SHAPED PART, THE MAJOR DIAMETER OF THE PART GIVEN BY V4DH SINE A+D2; AND EXERTING ON SAID CONICAL SHAPED PART COMPRESSION FORCES ACTING AROUND ITS AXIS AND TENSILE FORCES ACTING ALONG ITS AXIS TO GRADUALLY FORM THE CONICAL PART INTO TUBULAR SHAPED AND THEREBY FORM SAID TUBULAR SECTION AND EXERTING SAID FORCES SO AS TO MAINTAIN THE INCLUDED ANGLE IN THE UNWORKED PORTION OF THE PART AND TO CAUSE THE DIAMETER OF THE TUBULAR SECTION TO BE THE SAME AS THE MINOR DIAMETER OF SAID CONICAL-SHAPED PART, THE VARIABLES OF SAID FORMULA BEING DEFINED AS: D=THE MINOR DIAMETER OF SAID CONICAL SHAPED PART; H=THE HEIGHT OR LENGTH OF SAID TUBULAR SHAPE; AND A=1/2 THE INCLUDED ANGLE OF SAID CONICAL SHAPED PART. 